This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 壴 is uncertain. It appears as a component in characters like 鼓 (drum) and 喜 (joy), but its independent origin is unclear.
The shape combines 士 (samurai) over 口 (mouth) over 䒑 (a variant of 艹, grass). Picture a samurai standing over a mouth-like opening in the grass, but the meaning is unclear.
For シュ, imagine a shoe resting on the grass under the samurai's mouth: shoe -> シュ, though the kanji's meaning is uncertain.